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    <title>Document</title>
    <script>
        let setArr = new Set()// set里面不能有重复的值
        setArr.add('a');
        setArr.add('b');
        setArr.add('c')
        console.log(setArr);
        console.log('------------');
        setArr.delete('b');
        console.log(setArr);
        console.log('------------');
        console.log(setArr.has('a'));
        console.log(setArr.size);
        setArr.clear();
        console.log(setArr);
    </script>
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